Brand new phone useless and no one cares

I upgraded to an iPhone last year September and accidentally locked my Apple ID. I took the phone to Apple who can unlock it but won't without proof of ownership. I have gone into several MTN Stores, I have phoned them multiple times, I even went and waited for 2 hours in the queue at head office. No one can give me proof that I own this device and I have therefore not been able to use it despite paying for it. No one can assist and no one is interested in assisting. In store, I am told to phone as the upgrade was done via the phone. Via the phone, I am told they do not have record of the IMEI and there is nothing they can do. But MTN is still charging me for a device that is currently a very expensive paper weight.